It's a fact that no one really knows for sure whether recent global warming is a consequence of human action or not. However, there are two things that seem to be true. The first is that there seem to be a lot more scientists that think human pollution is the cause of global warming than the other way around (no, I don't have any hard data to corroborate this, so don't ask for it). Second, given that no one is actually sure about it, it seems the smart thing would be to play it safe, especially, when there's other excellent reasons reduce CO2 emissions like, say, for example breathing or oil depletion.
As such, this whole argument seems to be beside the point.